A sandwiched photoelectrochemical sensor for high-throughput single-cell analysis based on low-toxic and near-infrared AgInS2 microarray

High-throughput single-cell quantitative analysis is becoming increasingly important to elucidate cellular heterogeneity and further understand some related disease mechanisms. Various techniques including mass spectrometry, fluorescence detection, and electrochemiluminescence analysis have made significant progress in this area, but their dilemma is the destruction of cellular activity, the introduction of exogenetic probes and the resulting cellular metabolism perturbation, or the steric hindrance of the cells to the substrate. Here, we develop a non-destructive, probe-free, and hindrance-free photoelectrochemical (PEC) single-cell microsensor. First, a patterned PEC microelectrode with low-toxic and near-infrared AgInS2 microdots is simply fabricated by using a polydimethylsiloxane (PDMS) microstencil, exhibiting high photoelectric efficiency and low S2- detection limit (1.0 nM). Then, a PDMS microwell array is prepared for single cells trapping, matching the size of the microelectrode and with high single-cell occupancy (>93%). Finally, a sealed sandwiching platform is formed by aligning and clamping the two arrays, each microdot contacts with a single cell in one microwell and reacts with the secreted H2S, preventing the neighboring microwell's cross-contamination, cellular analyte's dilution, and cell's steric effect. The different light-addressable recorded photocurrent signals of all single cells directly reflect the 55.6% cell-to-cell differences. This report provides a useful and powerful tool to study single-cell heterogeneity.